1. Field of the Invention
The present invention relates to one of the eight isomers of 2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid, a compound which is an excitatory amino acid (EAA) neurotransmitter receptor antagonist useful as an anticonvulsant, analgesic, cognition enhancer, and neuroprotectant. When compared to the remaining seven ACPA isomers, the invented isomer is unexpectedly more potent in in vitro receptor binding assays and in in vivo efficacy studies.
2. Description of Related Information
The compound 2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid (ACPA) was described as an excitatory amino acid receptor antagonist in U.S. Pat. No. 4,761,405 which issued on Aug. 2, 1988. ACPA is a compound that has three asymmetric carbon atoms and thus eight stereoisomers. In U.S. Pat. No. 4,761,405 ACPA is reported as a racemic mixture of the eight isomers, and the in vitro and in vivo data presented to show efficacy as an excitatory amino acid receptor antagonist was generated by testing the racemic mixture. This patent does not include data showing relative activities of any of the eight isomers.